Another very tiny moth, Enteucha acetosae, is found in Britain. The smallest individuals have a wingspan of about 3 millimetres and the minute larvae live inside sorrel leaves, often turning them from green to red.

It is possible there may be even smaller moths out there, but we haven't found them yet. When an insect is this small, it has a very specific lifestyle, which makes it hard to study.

What are leaf miners?

One of the weirder parts of that lifestyle is leaf mining. Leaf miners are larvae that are so small, they live inside the plant tissue.

Normally, you can spot caterpillars sitting on leaves and stems, munching their way through them.

But as leaf miners eat the plant from the inside, they can't be easily seen. However the damage they cause can often be spotted as lines and blotches all over the leaf.

Other small moth species eat almost anything you could imagine including fungi, wood and underwater plants. The diversity is really amazing.

What do we know about the evolution of Lepidoptera?

Several micro-moths are long extinct - including Archaeolepis, a 180 million-year-old fossil. It was found in Dorset and is preserved in the Museum.

We also have some species that are very ancient, but are still alive today, which is fantastic. One of these families is called Micropterigidae. You can find Micropterix calthella in Ranunculus flowers in early June. Micropterigids are preserved in amber going back 125 million years or more.

These tiny moths are unique because the adults have chewing mouthparts. They chomp pollen grains or fern spores and grind them in a sort of gizzard.

It is fascinating because nearly all other moths and butterflies have sucking mouthparts - the proboscis - for drinking nectar.

Where do butterflies fit in?

Butterflies are (in the evolutionary scheme of things) just big, flamboyant, day-flying micro-moths.

Their fossils go back 55 million years, but recent research suggests they could have originated in the time of dinosaurs - between 110 and 65 million years ago.

They certainly evolved later than the tiny moths. They developed techniques for flying in the daytime, instead of at night like many moth species do.

What's next for micro-moth research?

We still hope that new, what we term, living fossils might be discovered. These are butterflies and moths that evolved a very long time ago, but are still going strong today.

In 2015, an extraordinary example of this was discovered: a micro-moth family called Aenigmatineidae, from Kangaroo Island near Australia.

The Museum has just acquired two precious specimens of the Kangaroo Island moth, Aenigmatinea glatzella.

Its mouthparts are atrophied and it does not eat, so the adults live only a few days. The species is clinging on in Kangaroo Island, living on bushes in a part of the island out of the reach of bush fires.

Research has shown that the family evolved very early, probably before the flowering plants were around - so they did not need to drink nectar.

Instead, the caterpillars live in the stems of a cypress plant.

It just goes to show that we live in really exciting times for Lepidoptera research - and there is still so much more to discover.